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I am Lao Zhou, I have repaired electronic devices for 15 years. Today, let’s talk about the seemingly simple yet profoundly knowledgeable topic of circuit board cleaning. A couple of days ago, a novice called me, saying he ruined a circuit board while cleaning it with alcohol, which gave me quite a scare! Beginners, you need to be cautious; there are many pitfalls here.
The Pitfalls of Alcohol Cleaning
Novices love to use alcohol for cleaning because it is cheap and easy to buy. But I must remind you, this is a fire pit!
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Alcohol Contains Water: The alcohol available on the market is generally about 75% pure, with the rest being water. This moisture remains on the board and can cause corrosion over time.
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Poor Cleaning Ability: Alcohol’s cleaning ability is quite limited for common stains like flux residue and rosin.
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Flammable and Explosive: Alcohol is highly volatile, and if not careful, it can easily cause a fire. I have seen someone smoking while cleaning with alcohol, almost setting the repair shop on fire.
The Advantages of Professional Cleaning Solutions
At this point, you might ask, “Lao Zhou, what should I use for cleaning?” The answer is professional water-based cleaning solutions.
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Strong Cleaning Power: Effectively removes various stubborn stains, even rosin is no match.
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Safe and Environmentally Friendly: Non-flammable, low toxicity, friendly to humans and the environment.
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Non-Damaging to Components: Specially formulated to avoid corrosion of electronic components and PCB boards.
I personally recommend the NW610 cleaning solution, which I have used for several years with excellent results. Remember, dilution ratio is crucial, generally 1:30, meaning 1 part cleaning solution to 30 parts water.
Ultrasonic Cleaners: The Cleaning Magic
Speaking of cleaning, I have to mention ultrasonic cleaners. This device is like giving the circuit board a bath, flushing out even the dust in the seams.
The Golden Rules for Parameter Settings:
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Frequency: Generally choose 35-40kHz; too high can damage components.
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Power: It is recommended to use 100-150W per liter of water; too much power can shake off components.
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Time: 5-10 minutes is sufficient; too long can have the opposite effect.
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Temperature: Room temperature is fine, do not exceed 40℃, otherwise, temperature-sensitive components may be damaged.
Precautions: Do not throw in modules with batteries; I have seen someone toss a battery-operated remote control in, resulting in battery leakage that contaminated the entire cleaning machine.
The Cleaning Process: Lao Zhou’s Secret Recipe
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Pre-treatment: Use a brush dipped in cleaning solution to lightly brush the surface dirt.
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Ultrasonic Cleaning: Place the board in the diluted cleaning solution and turn on the ultrasonic for 5-10 minutes.
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Rinsing: Rinse 2-3 times with deionized water or distilled water.
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Drying: Bake at around 40℃ for 10-15 minutes, or blow dry with compressed air.
Tips: After cleaning, check with a magnifying glass, especially under the IC pins, to ensure there are no residues.
Cleaning Taboo: Pitfalls to Avoid
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Do Not Use Tap Water: Mineral residue can affect board performance.
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Use High-Pressure Spraying with Caution: It can easily damage small components.
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Avoid Excessive Friction: It can scratch the PCB surface.
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Keep Away from Heat Sources: Do not blow dry directly with a hair dryer; I have seen someone blow off a chip.
Practical Exercise
Find a few scrap circuit boards to practice on. Try different concentrations of cleaning solution and feel the differences in cleaning effectiveness. Use a magnifying glass to observe changes before and after cleaning, paying special attention to the cleanliness around the solder joints.
Remember, circuit board cleaning seems simple, but doing it well can significantly increase your repair success rate. Practice more, and slowly you will master the skills. If you have any questions, feel free to ask me; Lao Zhou will always be your personal coach!